html{
    font-size: 62.5%;
}
body{
    color: #333;
    --site-width:100%;
    font-size: 1.2rem;
    line-height: 2rem;
}
h1,
h2,
h3,
h4,
h5,
h6,
ul{
    margin: 0;
    padding: 0;
}
li{
    list-style-type: none;
}
a{
    text-decoration: none;
    color: #333;
}
a:hover{
    color: #89211b;
}

img{
    max-width: 100%;

}
/*第一层布局 语义容器的宽度 */
header,nav,main,footer{
    width: calc(var(--site-width));
    margin: 0 auto;
}
/* 0-2.公共定义 */
.w1200{
    width: 120rem;
}
.fl{
    float: left;
}
.fr{
    float: right;
}
.cl{
    clear: both;
}
/* 1.页面顶部定义 */
header{
   background: #282828;    
}
.top_nav{
    display: flex;
    color: #a5a4a4;
    height: 30px;
    align-items: center;
}
.top_nav a{
     color:#a5a4a4;
}



